The subject matter disclosed herein relates generally to cryogenically cooled magnetic resonance imaging (MRI) systems, and more particularly to systems and methods for sealing a coldhead sleeve of the MRI systems.
In superconducting coil MRI systems, the coils forming the superconducting magnets are cryogenically cooled using a helium vessel. The cryogen cooling system of some of these MRI systems include a coldhead within a coldhead sleeve that operates to recondense vaporized cryogen to continually cool the superconducting magnet coils during system operation.
In conventional MRI systems, the coldhead sleeve is designed having an open end to a magnet cartridge, which is within a vacuum enclosure such that the open end is exposed to a helium vessel under pressure. When servicing or replacing the coldhead, service personnel remove the coldhead from the coldhead sleeve, thereby exposing the helium vessel to the atmosphere. When the MRI system is operating at high pressure, venting is needed to reduce the pressure. Thus, service personnel are exposed to high pressure and also the flush loss of helium from within the MRI system. Safety concerns exist particularly if the magnet in the MRI system quenches during coldhead servicing or replacement, resulting in boil off of helium.
Accordingly, the servicing of the coldhead in conventional MRI systems can be unsafe due to the high pressure environment. Additionally, helium from the helium vessel is lost and must be replaced, which results in added cost and further system maintenance.